Waterless or low water usage urinals have become more popular in recent years as the financial and environmental cost of supplying water becomes more important to water consumers. A number of different technologies are used in waterless urinals.
For example, in some cases, a conventional U-bend is used which utilises urine to provide a liquid barrier in the trap to prevent odours from the soil stack being emitted through the urinal.
There is a perception with urine barrier arrangements that the urine in the trap can itself result in unpleasant odours around the urinal. To alleviate this, one-way valves, such as duckbill valves, have been used to prevent the backflow of odours and, in the eventuality of a blockage, liquids.
The one-way valves on the market have drawbacks. For example, to provide sufficient sealing performance they are relatively long. In the confined space below a urinal it is sometimes necessary for these valves to be installed in a horizontal plane rather than in the vertical plane due to their length. Installation in a horizontal plane has a detrimental effect on the valve's efficiency. In addition, the conventional one-way valve can be awkward to marry-up to existing pipe work and, in some cases, to remove the valve for cleaning or replacement requires dismantling of the pipe work. As this pipe work can sometimes be concealed within the urinal, dismantling can be both awkward and time consuming.
In further cases, a urinal is adapted to receive a cartridge which is installed in a chamber at the base of the urinal. The cartridge contains a sealant liquid, usually an oil, which acts as a barrier between the urinal and the soil stack. When urine enters the urinal, the urine can pass through the sealant liquid and into the soil stack.
However, such waterless urinals have disadvantages. For example, the use of oil may be considered to be environmentally unfriendly and oil has associated disposal issues. There is also a significant amount of material in the cartridge which has to be replaced in its entirety periodically.